Electric-light illuminant.



.UNITED STATES PATENT OEFTOE.

ROBERTH. READ, OF SOHENEOTADnNEW YORKQASSIGNOR To GENERAL ELEOTRIO l oOMPANn'A CORPORATION OF NEW YORK.

ELECTRIC-LIGHT ILLUMINANT.

Specification of Letters Patent.

Patented .my 9, 1907.

Application filed September 16,19041 Blilil NO- 224,648.

To` all 'whom at 'may concern:

Be it known that I, ROBERTH. READ, a citizen ofthe United States, residing atSchenectady, in the county oi Schenectady and State of Newl York, have invented certain new and useful Improvements in Electricj Light Illuminantaof which the following is a specification.

This invention relates to electric lighting, and its object is to provide a light-emitting element capable oi yielding a brilliant white light with a high degree oi efficiency. To this end, I construct the illuminant of magnesium carbid. y This substance was first produced illuminant. v In the accompanying drawing, Figure l shows an4 by Moissan in 1898, by acting on heatedmagnesium with a stream of acetylene (Comptes Rendus, Vol. 126, pp. 3D2-306), -but so far as I am aware no one has heretoiore discovered its advantages as an electric-light electric-light illuminant made of magnesium carbid, in the formof an arc-light electrode; Fig; 2 is a longitudinal section of an-electrode showinga carbon jacket or' tube with a core of magnesium carbid; and Fig. 3 shows an electrode of magnesium carbid with a jacket or coating of metal.

The electrode shown in Fig. 1 is a cylindrical stick j 2 1 oi suitable length and diameter to be substituted for the ordinary carbon velectrodes used in arc lamps. It is composed of magnesium carbid, which is first granulated and mixed with tar or other carbonaceous binder,

and then molded in a powerful press. Powdered carbon or. refractory oxids or metals may be mixed with the carbid beforemolding in order to facilitate the starting ofthe arc, or to modify the light. A conducting diluent such as carbon promotes a better action in an ordinary arc lamp in preventing mushrooming of the magnesia formed by combustion in 'ai'.r.

-Instead of making the entire electrode o carbid, the latter may be used alone or kmixed with carbonaceous or other materials as a core orlling for a tubular carbon electrode, as shown in'Fig. 2, where the magnesium carbid core 2 is inclosed in the tubular carbon jacket 3; the latter being shown in section. 1f necessary, the electrode of magnesium carbid or a mixture containing the same may be incasedin'or plated with metal', as api pears in Fig. 3, where such a jacket or coating is shown in se'ction at 4.

When magnesium carbid is burned, a refractory oxid is left which may be removed from the electrode, when the arc is again struck, by imparting a wiping move-A ment to the electrodes, or by striking the arc from a part of the electrode back of the top. 4

An electrode of the kind describedmayl be used at both positive and negative sidesor only one such bev employed together with either carbon or metal electrodes. The arc produced gives the spectrum characteristic of magnesium and a laiger proportion lies within the visible range o f the spectrum than any other source of artificial light, thus greatly enhancing the luminous efliciency. A' further advantage for electrode purposes ofmagnesium carbid arises from the fact that it is not readily decomposed by the moisture of the atmosphere.

What I claim as new and desire to secure by Letters Patent of the United States, is, v

1. An arc-iight electrode containing magnesium carbid.

2. An arc-light electrode containing magnesium carbid mixed with a diluent. Y

3. An arc-light electrode containing magnesium carbid mixed with a conducting diluent.

4. An arc-light electrode comprising a molded pencil containing magnesium carbid. y

5. An arc light electrode .consisting mainly of niagnesium carbid. A

In witness whereof, I have hereunto set my hand this fifteenth day of September A. D., 1904.

" A ROBERT H. READ.

Witnesses:

BENJAMIN B. HULL, HELEN ORFonD. 

